Oil bleaching method



Sept. 6, 1955 C. E. MCMICHAEL ET AL OIL BLEACHING METHOD Filed Aug. 28, 1951 my. l.

www L ATTORNEYS United States Patent O 2,711,256 s ouJ BLEACHING METHOD Charles E. McMichael, John W. Godbey, and Victor L.

Zehnder, Louisville, Ky., assignorrs, by mesne assignments, to National Cylinder Gas Company, Chicago, Ill., a corporation of Illinois Application August 28, 1951, SerialNo. 244,016

9 claims. (Cl. 26o-42s) This invention relates to the'bleaching of oils, especially fatty-oils and fats, for instance cotton seed oil, soya bean oil and the like intended for use 4in various ways, such as in food products.

The invention is concerned with equipment and method adapted to utilize a bleaching adsorbent, for instance carbon black or bleaching clays such as fullers earth.

In the bleaching of oils with a bleaching adsorbent it is of course necessary to effectA intimate contact between the oil and the adsorbent, and this usuallyiinvo-lves dispersing the adsorbent in the oil,at least at one stage o f the bleaching operation. The physical intermixing of adsorbent, ordinarily consisting of a nely powderedmaterial with the oil presents probelms from the standpoint of handling and ensuring the desired degree of intimacyof admixture or uniform dispersion ofthe adsorbent in'the oil. One of the important objects of the present invention is concerned with the facilitation of the handling of the adsorbent and the obtaining of intimacy-of contact thereof with the oil. y

The invention is also of special utility when used in a bleaching system where the adsorbent and the oil are brought together in counterow in which respect the invention is in the nature of an improvement on vthe method disclosed in the copending application of Alton E. Bailey, Serial No. 58,327, filed November -4, 1948, now Patent Number 2,618,644, issued November 18, 1952. In said Bailey application, the oil is tirstsubjected toa bleaching treatment withV partially spentadsorbent, `and is thereafter subjected to treatment with fresh adsorbent, which latter is then separated from vthe oil and used for the irst stage of bleaching of additional unbleached oil. The invention facilitates the vmultistage use of the adsorbent.

Another problem encountered in bleaching systems using an adsorbent arises because of the `desirability of deaerating and dehydrating both the-oil and the adsorbent prior to the intercontact thereofat an elevated temperature, since the subjection of oils of the kind here involved to high temperatures in the presence of substantial quantities of air or `of moisture is undesirable, usually having a deleterious effect upon the oil itself. With these Vgeneral problems in mind, the invention also contemplates certain improvements which not only facilitate the handling ofthe adsorbent but which provide at the same time for subjecting the adsorbent to deaeration and dehydration prior to contact With the oil at a high temperature. Thus, according to the preferred practice of the invention the fresh adsorbent is initially mixed with a small quantity of .oilwhich has been previously subjected at least to deaeration and kdehydration and preferably also to at least some bleaching treatment. In this way a slurry is formed in which the oil is substantially free of air and moisture, and thisV slurry is dispersedin space and treated with stripping steam prior to .admixture with the oil to be bleached. This facilitates the handling of the dry, powder adsorbent material the deaeration of the Patented Sept. 6,` 19,55

. 2 adsorbent itself and alsofacilitates the admixture of the adsorbent with the oil to be bleached.

How the foregoing objects and advantages are attained will appear more fully from the following description referring 'to theaccornpanying drawing, in which- Figure 1 is a somewhat schematic view of an oil bleaching system arranged according tothe invention; and

Figure 2 is a view illustrating a modification of one portion of the equipment shown in Figure 1.

As appears in Figure 1, an adsorbent supply bin or the like is indicated atv3. `The adsorbent is delivered from this'bin into a vessel 4 equipped with a mixer 5, and in the vessel 4 the adsorbent is mixed with a small amount of oil in order'to produce .a slurry. This slurry may then be strained as at 6 and delivered through a disvpersingA or spray-type nozzle 7 located inthe upper porper and lower chambers being divided by a partition 11. A stand pipe 12 extends upwardly from the partition 11 and serves to interconnect the upper region of the lower chamber 10 with the mid or upper region of the upper chamber 8, for a purpose to bedescribed more fully hereinafter.

' The o`il to be bleached is introduced into the system through the supply connection 13 from which it is pumped to a spray inlet nozzle 14 arranged in the upper portion of 'the lower chamber 10. The oil is preferably intro- Aduced into this chamber at a somewhat elevated temperature,.for-instance from l" F. to 160 F., and during the falling of the oil particles to the body of oil in `the bottom of chamber 10, the oil particles are subjected to thek action of stripping steam which is'introduced through the perforated pipe or the like 15 located in the bottom of this chamber. Stripping also occurs during the residence of the oil inthe bottom ofthe chamber.

At thetop of the vessel 9, communicating with the upper portion of the upper chamber 8, is a vacuum otake V. Because of the provision of the stand pipe 12 .the vacuum is drawn not only in the upper chamber y8 but' also in the. 'lower chamber 10, and the result of this `arrangement is' to effect steam stripping under vacuum ofthe oil discharged from the nozzle 14, thereby effecting deaeration and dehydration ofthe incoming oil in the lower chamber. The oil is withdrawn from chamber 10 at .the bottom thereof through a strainer 16 and is then pumped through aheat exchanger 17 and a heater 18,\and from thereis ydelivered to one or anotherof the filters F1, F2 andy F3.

Y `Assuming flow through the' tlter F1, it should rbenoted .that this filter contains a cake or mass of partially spent bleaching vadsorbent through `which the oil is passed. As the heated, unbleached oil passes in contact with the partially spent, massed adsorbent, it gives up a substan- 'tial amount of its color to the adsorbent, and thereby is subjected to a rst stage of bleaching. From the filter,

the partially bleached oil passes to the connection 19 which extends through branches and valves to an oil inlet 20- located below the surface of the body of oil in the bottom of the upper chamber 8 of the treatment vessel 9. Here the partially bleached oil is mixed with the slurry of oil and fresh adsorbent introduced through the inlet 7, and the second or nal bleaching stage is accomplished.

.from the filter .F2` through line 23 to heat exchanger 17,

where it passes in heat exchange with the cooler oil being pumped from the lower chamber 10 to the filter F1. The connection 24 from the outlet side of the exchanger 17 extends to a cooler 25, from which the completely bleached oil may be pumped to storage through the storage line It should be understood that after the build up of a filter cake in the press F2, the oil flow from the upper chamber 8 of the treatment vessel 9 may be diverted to one of the other filters, for instance filter F3, and at this time the oil flow from the lower chamber 10 may also be diverted from the filter press F1 to the filter press F2. With a system of filter presses and connections as described above, the individual filters may be rotated, so to speak, in their use and when one is out of service it will of course be cleaned and then intially re-used to separate adsorbent from the oil withdrawn from the upper chamber 8, and thereafter used for the passage therethrough and treatment of oil withdrawn from the lower chamber 10 of the vessel 9.

Returning to the arrangement in the upper chamber 8, it is now noted that the steam which is introduced into the lower chamber and flows upwardly through the stand pipe 12 is withdrawn upwardly through the vacuum connection V, and in passing upwardly through the free space in the upper chamber 8 this steam is used in assisting the separation of air and moisture from the incoming and dispersed slurry of adsorbent and oil admitted through the inlet 7. Additional stripping steam may be introduced into the lower portion of the upper chamber 8 as by the perforated pipe 27. This latter steam also serves to agitate the mixture of oil and adsorbent during its residence in the bottom of chamber 8. The oil may also be heated in the upper chamber 8 by means of the steam heater coil 28.

By arranging the ow of oil through the upper and lower chambers of the vessel 9 in the manner described above, i. e., initial ow through the lower chamber, in the event of any overow of oil from the upper to the lower chamber, no contamination of bleached oil will occur, as the oil from the lower chamber is not yet bleached and will be delivered to one or another of the filter presses and ultimately to the upper chamber.

lt may be noted that the temperature of the oil leaving the lower chamber is preferably raised in the heat exchanger 17 and the heater 18 to an effective bleaching temperature, for instance in the neighborhood of 250 F. Some loss in temperature may occur in passage through the filter in which the first stage of bleaching takes place, but the oil delivered from the filter system to the upper chamber 8 (through the inlet 20) will still have a fairly high temperature, effective for bleaching as this oil is admixed with the fresh bleaching adsorbent.

A branch line 19a is provided in cases where it is desired to recirculate all or a portion of the oil after the initial bleaching in the filter press system, this connection 19a delivering into the lower chamber 10.

As hereinabove indicated it is preferred to utilize oil which has at least been deaerated and dehydrated in preparing the slurry in vessel 4. For this purpose completely treated oil, for example about 16% of the total flow through the system may be diverted from the storage line 26 through the connections 29 and 30 and thereby delivered to the mixing Vessel 4. If desired some or all of the oil used in preparation of the slurry may be derived from the lower chamber 10 of the treatment Vessel 9, a connection 31 being provided for this purpose, Which connection (31) communicates with the connection 30.

Still further, particularly after shutdowns, the initial slurry to be used may be prepared by using completely untreated oil derived from the supply line 13 and delivered to the mixing vessel 4 through the connection 32. Under some circumstances, it is contemplated that in preparing the .slurry it may even be dgirabl? .t9 11S? untreated oil in theinitial slurry in normal operation of the system.

In Figure 2 a modified arrangement is illustrated in which the inlet 20a for oil delivered from the filter press system to the upper chamber takes the form of a spray-type of nozzle arranged above the level of the oil in the bottom of the upper chamber 8. By this arrangement the oil introduced into the upper chamber 8 may also be subjected to some steam stripping in space.

It will be understood that level and other controls are of course provided in the system in a manner which need not be described in detail herein.

From the foregoing it will be seen that a novel and improved mode of handling and of deaerating and dehydrating the adsorbent is provided according to the invention, and that the method steps and equipment utilized for the handling, deaerating and dehydrating of the adsorbent are integrated into a system of the counterflow type wherein the oil is subjected to a plurality of steps of bleaching, the same bleaching adsorbent being used in counterflow.

We claim:

l. In a process for bleaching oil with a bleaching adsorbent, which includes the steps of subjecting the oil to the bleaching action of partially spent bleaching adsorbent, mixing the partially bleached oil thus obtained with fresh bleaching adsorbent, and separating the resulting partially spent adsorbent therefrom for use in bleaching additional oil according to the first bleaching step, the improvement which comprises forming a slurry by mixing a fractional portion of the fully bleached oil with fresh adsorbent and adding this slurry to the partially bleached oil in the second bleaching step.

2. A method according to claim 1 in which the admixture of fresh adsorbent with said fractional portion of the fully bleached oil is preliminarily subjected to contact with stripping steam prior to use thereof in the second bleaching stage of claim 1, and further in which the fresh oil is subjected to the action of stripping steam prior to bleaching thereof in accordance with the first bleaching step of claim 1 and in which said stripping steam is thereafter used in the preliminary treatment of the admixture of fresh adsorbent and cil.

3. A method according to claim 1 in which the slurry is subjected to steam stripping under vacuum to effect dehydration and deaeration thereof prior to admixture with the oil in the second stage of bleaching.

4. A method according to claim 1 in which the admixture of fresh adsorbent with said fractional portion of the fully bleached oil is preliminarily subjected to contact with stripping steam prior to use thereof in the second bleaching step of claim 1.

5. A method for bleaching oil with a bleaching adsorbent comprising mixing fresh adsorbent with a small amount of oil to form a slurry, dispersing said slurry in space and subjecting the dispersed slurry to the action of stripping steam to effect deaeration and dehydration of the adsorbent, mixing the deaerated and dehydrated adsorbent with partially bleached oil to effect a second stage of bleaching thereof, filtering the adsorbent from said oil, and subjecting fresh oil to a first stage bleaching by contact with the bleaching adsorbent separated by the filtration.

6. A method according to claim 5 in which the fresh oil is preliminarily subjected to the action of stripping steam to effect deaeration and dehydration thereof prior to the first stage bleaching thereof.

7. A method according to claim 5 in which the fresh oil is preliminarily subjected to the action of stripping steam to effect deaeration and dehydration thereof prior to the first stage bleaching thereof, and in which the oil used in preparing the slurry referred to in claim 8 is deaerated and dehydrated oil.

8. A method according to claim 7 in which the strip- 7 5 ping steam used for deaeration and dehydration of the fresh oil is subsequently used for deaeration and dehydration of the fresh adsorbent contained in said slurry thereof.

9. In a process for bleaching oil wherein the oil is subjected to the action of a partially spent bleaching adsorbent in a rst stage bleaching operation and wherein the partially bleached oil is subjected to a second stage bleaching operation by admixture with fresh bleaching adsorbent, and further wherein the partially spent bleaching adsorbent is separated from the oil following said second stage bleaching and the separated partially spent adsorbent is used in the first stage of bleaching, the improved method comprising mixing a fractional portion of the fully bleached oil with the fresh adsorbent to form a slurry, this mixing being effected with the oil at a temperature below effective bleaching tempera- References Cited inthe le of this patent UNITED STATES PATENTS 779,022 Bataille Jan. 3, 1905 1,474,062 Bollmann Nov. 13, 1923 1,849,653 Baylis Mar. 15, 1932 2,116,344 Dunmire May 3, 1938 2,401,338 Dunmire June 4, 1946 2,555,098 Sanders May 29, 1951 2,577,079 Gee Dec. 4, 1951 2,618,644 1952 Bailey g.; Nov. 1s, 

1. IN A PROCESS FOR BLEACHING OIL WITH A BLEACHING ADSORBENT, WHICH INCLUDES THE STEPS OF SUBJECTING THE OIL TO THE BLEACHING ACTION OF PARTIALLY SPENT BLEACHING ADSORBENT, MIXING THE PARTIALLY BLEACHING OIL THUS OBTAINED WITH FRESH BLEACHING ADSORBENT, AND SEPARATING THE RESULTING PARTIALLY SPENT ADSORBENT THEREFROM FOR USE IN BLEACHING ADDITIONAL OIL ACCORDING TO THE FIRST BLEACHING STEP, THE IMPROVEMENT WHICH COMPRISES FORMING A SLURRY BY MIXING A FRACTIONAL PORTION OF THE FULLY BLEACHING OIL WITH FRESH ADSORBENT AND ADDING THIS SLURRY TO THE PARTIALLY BLEACHING OIL IN THE SECOND BLEACHING STEP.
 5. A METHOD FOR BLEACHING OIL WITH A BLEACHING ADSORBENT COMPRISING MIXING FRESH ADSORBENT WITH A SMALL AMOUNT OF OIL TO FROM A SLURRY, DISPERSING SAID SLURRY IN SPACE AND SUBJECTING THE DISPERSED SLURRY TO THE ACTION OF STRIPPING STEAM TO EFFECT DEAERATIONAND DEHYDRATION OF THE ADSARBENT, MIXING THE DEAREATION AND DEHYDRATED ADSORBENT WITH PARTIALLY BLEACHING OIL TO EFFECT A SECOND STAGE OF BLEACHING THEREOF, FILTERING THE ADSORBENT FROM SAID OIL, AND SUBJECTING FRESH OIL TO A FIRST STAGE BLEACHING BY CONTACT WITH THE BLEACHING ADSORBENT SEPARATED BY THE FILTRATION. 